I though I would share with you my experience of getting GCSE papers remarked as it may help others decide if it's worth the money or not.
We asked for 3 subjects to be remarked, chemistry 3 papers, history 2 papers, English lit 2 papers.
Chemistry DS need 3 marks to go up a grade, one paper went down 2 marks each of the other 2 went up 1 mark. Result same marks/grade as before.
History DS needed 3 marks to go up a grade, one paper went down by 13 marks, second paper went up 6 marks. Results Mark went down by 7/grade stayed the same.
English Lit needed 8 marks to go up a grade. Only heard back from one paper so far which has gone up 10 points. Result he has gone up a grade as this was a whole school remark in this subject which means you will not go down a grade.
I'm glad we did have the papers remarked, but rather shocked by the amount the marks can go up and down.